1. Field
The following description relates to localization technology, and more particularly, to an apparatus and method for recognizing a position using range signals.
2. Description of the Related Art
A related art range only (RO) sensor refers to a sensor sensing signals received using a global positioning system (GPS), an ultra wideband (UWB), and Wireless Fidelity (Wi-Fi), the received signals only indicating a distance from a range landmark.
Different from a landmark using an image, the related art RO sensor has its own identifier, making it distinguishable from other landmarks. However, the related art RO sensor does not have angular information between a position recognizing apparatus and a landmark, and only has range information between the related art RO sensor and a range landmark. Accordingly, even if the position of the range landmark is estimated using the sensed range information and the travelling distance of the position recognizing apparatus, the sensed distance and the travelling distance of the position recognizing apparatus each have errors, also causing errors in estimating the position of the range landmark.
In the related art, to optimize the errors of the sensed distance and the travelling distance of the position recognizing apparatus at the same time, a simultaneous localization and mapping (SLAM) algorithm is used. The SLAM algorithm represents an algorithm which enables simultaneous estimation of the position of a position recognizing apparatus and a map of an environment of the position recognizing apparatus by repeating a consecutive motion including building a map of the environment of the position recognizing apparatus and localizing the position recognizing apparatus, which has moved to a new position, based on the built map.
FIG. 7 is a diagram illustrating the related art probability distribution of the existence of a range landmark expressed in a Gaussian distribution, when the range landmark is expressed in a Cartesian coordinate system.
The related art RO sensor senses only the distance between the position recognizing apparatus and the landmark, so the probability distribution of existence of the range landmarks is expressed as a circular band. As shown in FIG. 7, if the position recognizing apparatus 10 exists at a position A, the probability distribution of existence of the range landmark is a circular band 1. If the position recognizing apparatus 10 exists at a position B, the probability distribution of existence of the range landmark is a circular band 3. If the position of the range landmark is estimated while the position recognizing apparatus 10 is moving from the position A to the position B, the probability distribution of the range landmark is reduced and converges, and finally the position of the range landmark is estimated.
In this case, if the position of the range landmark is modeled in the Cartesian coordinate system such as Lx, Ly, the probability distribution of the existence of the range landmark may be modeled as a Gaussian distribution 7 for an estimated range landmark 5. However as the probability distribution of the existence of a range landmark is modeled as a Gaussian distribution for a range landmark modeled in a Cartesian coordinate system, the Gaussian distribution has a shape deviating from the circular ring type distribution, causing errors in estimating the position of the range landmark. In addition, if a probability distribution model having a circular ring shape is modeled into a plurality of Gaussian distribution models, the computation required for estimating the position of the range landmark is increased, thereby requiring substantial computing resources and time in estimating the range landmark.